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Engine basics => Engine set up tips => Topic started by: Robin_Holden on February 21, 2011, 06:37:48 AM

Title: Brodak B40 : Best props' & Launch RPM ?
Post by: Robin_Holden on February 21, 2011, 06:37:48 AM
Greetings fellas , I'm sure this has been discussed before but I would really appreciate some input please.

I've run-in my B40 on the bench and she's now installed in a Sig Banshee , with the nose shortened so no C of G problems.

What prop' do you recommend please ?
What launch RPM would apply ?

I've fitted an MAS 10X5 at the moment .Fuel will be 23% lube' [ around 70% synthetic / 30% castor ].
I'm using a plastic R/C tank with uniflow plumbing.

Much obliged for any contributions ,

Robin.
Title: Re: Brodak B40 : Best props' & Launch RPM ?
Post by: Bill Barber on February 21, 2011, 08:53:48 AM
    Robin in my ARF Nobler with a Brodak 40 using an APC 10.5 x 4.5 prop ,
launching at 10200 RPM's . Fuel is 10% nitro - 22% syn.oil & castor blend .
              Bill
Title: Re: Brodak B40 : Best props' & Launch RPM ?
Post by: Brian Massey on February 21, 2011, 11:19:38 AM
Robin; I have a B40 in a Sig Super Chipmonk that tips the scales at 51.5 oz. I've used an RSM 10/6 with great results. Launched at about 9700 on 62' lines (eye to eye) and got about 5.0 sec laps with a great 4-2 break. I snagged a dandylion on one takeoff and broke the prop. Put on a Vess 10/6 and had to work the launch rpm up to 10500 before I got my speed back, but for the most part, lost the 4-2 break. Next I put on an old paddle blade Top Flite 10/6 from the 60's . . . nearly identical in performance to the RSM. I just received an order that includes new Top Flite props; I'm hoping to test one tomorrow. With this setup, I can get the pattern in on about 120cc of 10/22 fuel.

Hope this helps.

Brian
Title: Re: Brodak B40 : Best props' & Launch RPM ?
Post by: Clint Ormosen on February 21, 2011, 08:39:12 PM
I have a few models with a B-40 in them. My Chipmunk uses a BY&O 11-5 @9500rpm and my Sig mustang uses a Bolly Clubman 10.5-5 @10600 rpm. Right now I'm experimenting with a MA 10-5 3 blade on my Tempest and so far so good @10200 rpm.

In all cases I've been using Powermaster 10/22 fuel and Thunderbolt R/C long plugs.
Title: Re: Brodak B40 : Best props' & Launch RPM ?
Post by: Robin_Holden on February 22, 2011, 01:25:57 AM
Very much obliged for your contributions guys ,

Kind regards from the Charente ,

Robin.